Shredding devices are used to shred cellulosic (e.g. wood, paper, etc.) and plastic materials at waste disposal reclamation or recycling sites. There are continuous and batch type shredders. Continuous shredding devices are adapted to continuously receive a feed material and exhaust shredded material. The continuous shredding devices are generally capable of handling large volumes of feed materials. In contrast, batch or non-continuous shredding devices process the material on a batch-wise basis until the desired shred at which point the shredded material is dumped and a fresh batch of unshredded material is added to the shredder.
Low cost shredding devices which rely upon an initial cutting or shearing stage followed by a secondary shredding stage are commercially available. These shredding devices are generally limited in material handling capability or shredding applicability. Devices useful for shredding paper products are often unfit for shredding wood or plastic materials and vice versa. Certain inexpensive paper shredding devices shred paper into elongated strips which, although useful for the destruction of confidential or business documents, such shredded products are nominal in value.
In contrast to the aforementioned devices which initiate waste material processing by cutting, certain devices which rely upon initially grinding or crushing a wide variety of materials such as plastics, wood, paper, rock metal, coal, limestone, etc. Such devices are prohibitively expensive and are restricted to large recycling or reclamation sites having a sufficient abundance of waste materials (e.g. such as may be obtained through waste collection and disposal in the large metropolitan areas) to override the expenses. It is not economically feasible to utilize these devices at suburban, rural or small town waste recycling or reclamation sites which are not in close proximity to a large metropolitan area or an otherwise abundant source of waste materials.
Large paper reclamation or disposal sites may also combine their paper shredding operation with baling devices which bale shredded paper into a large bale size (e.g. 1/2 ton size or larger) for resale primarily to paper manufacturers. The supply of such shredded products exceeds the demand. Consequently, there exists marginal profits for such shredded paper producers.
There currently exists a substantial demand for bedding (e.g. straw, chopped corn stocks, saw dust, etc.) within the livestock and poultry producer trade. Paper shredded to the proper bedding size (at an attractive processing cost in close proximity to such livestock and poultry producers) would alleviate a substantial waste disposal problem and significantly enhance the waste paper recycling profitability. More profitable margins would arise if it were possible to convert such paper products into a functional and useful bedding form at the smaller and more rural processing sites via inexpensive equipment possessing multi-waste material processing efficacy.
The patent literature discloses numerous shredding devices. Illustrative thereof is U.S. Pat. No. 4,350,308 to Brewer which discloses a shredding machine for mounting to a revolving shaft, a blade-holder with a radially outwardly projecting protuberance having a forwardly-facing blade-backing surface, a slot having opposed surfaces, a blade seated in the slot engaging said opposed surfaces and disposed against said blade-backing surface, wherein said blade has a work-impact forward surface positioned above said slot, and elongate securement means disposed above and outside said slot and projecting through said blade, and into said protuberance.
U.S. Pat. No. 4,850,408 to Carpenter et al discloses a wood chipper apparatus having a rotating chipper disc and one or more knives mounted on said disc to produce wood chips upon feeding wood material against the disc.
U.S. Pat. No. 4,706,898 to Schonfeld et al discloses a crushing machine with a removable outlet grate, wherein the outlet grate is disposed between the crushing machine housing extending horizontally between a pair of opposite walls, and an opening is provided in at least one of the opposite walls in the vicinity of the rate, to enable said grate to be removed in whole or in part through the opening.
Other illustrative patents of interest which appertain to particle reduction devices include: U.S. Pat. No. 1,921,914 to Edman; U.S. Pat. No. 3,561,685 to Feder; U.S. Pat. No. 4,071,198 to Tetreault; U.S. Pat. No. 4,168,035 to Palm et al; U.S. Pat. No. 4,422,353 to Hull et al; and U.S. Pat. No. 4,736,781 to Morey et al.
Wood chipping devices of a rotating disc type are known. Devices such as the Eklund et al wood chipper (see U.S. Pat. No. 3,384,311), the aforementioned Carpenter et al device (U.S. Pat. No. 4,850,408), the Valby wood chippers and other similar type chippers characteristically rely upon rotating knives affixed onto a rotating disc having passageways through which the chipped wood pieces from the knives are transferred through the passageways into a secondary processing chamber for further processing. These devices are relatively inexpensive and commonly used by governmental units and private industry in the disposal of wood trimmings.